Acquisitions - Additional Information (Details) $ / shares in Units, $ in Millions	Jul. 15, 2014 USD ($) $ / shares shares
112 West 34th Street
Business Acquisition [Line Items]
Total consideration paid	$ 423.6
Debt assumed	87.7
Payments to acquire businesses, gross	106.9
Consideration transferred, equity issued	$ 229.0
Business acquisition, share price (in dollars per share) | $ / shares	$ 16.65
112 West 34th Street | Class A Common Stock
Business Acquisition [Line Items]
Equity issued, number of shares | shares	1,217,685
112 West 34th Street | Class B Common Stock
Business Acquisition [Line Items]
Equity issued, number of shares | shares	77,945
112 West 34th Street | Series PR OP Units
Business Acquisition [Line Items]
Equity issued, number of shares | shares	12,457,379
1400 Broadway
Business Acquisition [Line Items]
Total consideration paid	$ 310.0
Debt assumed	80.0
Payments to acquire businesses, gross	79.7
Consideration transferred, equity issued	$ 150.3
Business acquisition, share price (in dollars per share) | $ / shares	$ 16.65
1400 Broadway | Class A Common Stock
Business Acquisition [Line Items]
Equity issued, number of shares | shares	1,338,488
1400 Broadway | Class B Common Stock
Business Acquisition [Line Items]
Equity issued, number of shares | shares	32,452
1400 Broadway | Series PR OP Units
Business Acquisition [Line Items]
Equity issued, number of shares | shares	7,658,516